From the FDA Drug Label
Haverhill fever, Rat-bite fever 12 to 20 million units/day for 3 to 4 weeks* Rat-bite fever; Haverhill fever (with endocarditis caused by S moniliformis) 150,000 to 250,000 units/kg/day in equal doses every 4 hours for 4 weeks The recommended treatment for a patient diagnosed with Rat-bite fever is Penicillin G administered:
- For adults: 12 to 20 million units/day for 3 to 4 weeks
- For pediatric patients: 150,000 to 250,000 units/kg/day in equal doses every 4 hours for 4 weeks 1
From the Research
The recommended treatment for rat bite fever is immediate antibiotic therapy, with penicillin G as the first-line treatment, administered intravenously at 1.2 million units every 4 hours for 7-10 days in severe cases, followed by oral penicillin V 500 mg four times daily to complete a 14-day course, as supported by the most recent study 2. The choice of antibiotic is crucial in treating rat bite fever, which is caused by Streptobacillus moniliformis or Spirillum minus, and penicillin is typically effective against these organisms 3. For penicillin-allergic patients, doxycycline 100 mg twice daily for 14 days is an effective alternative, as shown in previous cases 4, 5. Treatment should begin promptly after diagnosis, even before culture results, as delayed therapy can lead to serious complications including endocarditis, meningitis, or septic arthritis, with a mortality rate as high as 13% without proper treatment 6. Supportive care including pain management, hydration, and fever control should accompany antibiotic treatment, and patients should be monitored for potential complications, particularly those with heart valve abnormalities who may require longer treatment courses to prevent endocarditis. Key points to consider in the treatment of rat bite fever include:
- Prompt initiation of antibiotic therapy
- Use of penicillin G as the first-line treatment
- Alternative use of doxycycline for penicillin-allergic patients
- Supportive care for pain management, hydration, and fever control
- Monitoring for potential complications, especially in patients with heart valve abnormalities. It is essential to note that rat bite fever can be easily misdiagnosed due to its nonspecific initial presentation, and a high index of suspicion is necessary for early diagnosis and treatment, as highlighted in the study 2.